Firing mechanism with integral safety



A e 1965 A. L. MONTANA FIRING MECHANISM WITH INTEGRAL SAFETY 3 Sheets-Sheet 1 Filed Feb. 17. 1964 8" 1965 A. 1.. MONTANA 3200,709

FIRING MECHANISM WITII INTEGRAL SAFETY F'iled Feb. 17. 1964 3 Sheets-Sheet 2 8" 1965 A. 1.. MONTANA 3200,709 FIRING MECHANISM WITH INTEGRAL SAFETY Filed Feb. 17, 1964 3 Sheets-Sheet 3 United States Patent C) FIRING MECHANSM WTH INTEGRAL SAFETY Alfred L. Montana, East Longmeadow, Mass., assignor to the United States of America as represented by the Secretary of the Anny Filed Feb. 17, 1964, Ser. No. 345,537 Claims. (Cl. 89-142) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for govemmental purposes without the payment to me of any royalty thereon.

This invention relates to firearms and more particularly to the firing mechanisms thereof.

It is the object of this invention to provide a firing mechanism whereby a firearm may be selectively fired automatically in open bolt position or semiautomatically in closed bolt position with the automatic sear acting as a safety to assure that the hammer cannot be released if the trigger is repuiled before the bolt reaches battery when the firearm is fired semiautomatically.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is a fragmentary, longitudinally cross-sectioned view of a rifle showing the firing mechanism indexed for semiautomatic lire and the hammer released to the striking position;

FIG. 2 is a view taken along line 2-2 of FIG. 1;

FIG. 3 is a view taken along line 3-3 of FIG. 1;

FIG. 4 is a fragmentary view similar to FIG. 1 but showing the hammer held retracted by the primary sear;

FIG. 5 is a view taken along line 55 of FIG. 3;

FIG. 6 is a view similar to FIG. 5 but showing the selector indexed for automatic fire;

FIG. 7 is a fragmentary view sirnilar to FIG. 4 but showing the selector indexed for automatic fire and the bolt releasably held in open bolt position by the bolt sear;

FIG. 8 is a view taken along line 8-8 of FIG. 7;

FIG. 9 is a perspective view of the selector; and

FIG. 10 is an exploded, perspective view of the sliding block and primary sear assembly.

Shown in the figures is a firearm 12 having a receiver 14 in which a bolt assembly 15 is mounted for reciprocation between a forward battery position and a rearward recoil position. Bolt assembly 15 includes a bolt 16 carried by a slide member 18 and a firing pin 20 slidingly disposed in the bolt.

A trigger housing 22 with a depending pistol grip portion 24 is replaceably mounted on the bottom side of receiver 14. Trigger housing 22 includes an integral fiange 26 which extends longitudinally forward along the bottom of receiver 14 when the trigger housing is mounted t-hereon. Trigger housing 22 is channeled out from the top thereof above pistol grip 24 and along fiange 26, as noted at 28, to house the firearm firing mechanism.

The firing mechanism includes a pivotal trigger 30, a hammer 32, which is pivotally mounted on a transverse pin 33 and is biased by a spring 34 from a retracted position to a striking position against the rear end of firing pin 20, when bolt assembly 15 is in battery position, and a selector 36 which is designed, as hereinafter described, for selectively indexing the firing mechanism for automatic and sernautomatic fire and to safety the iring mechanism against accidental discharge by trigger 30. Hammer 32 is pivotally retracted by carnrning contact of the head of the hammer, noted at 38, by the rear end of slide mernber 18 during travel thereof to the recoil position.

Semiautornatic fire is achieved through a searing mechanism which includes a longitudinally sliding block 40 having a front end 42 carnmingly contactable with the rear side of trigger so as to be displaced rearwardly when the trigger is pulled. Block 40 is biased forwardly by a spring 44. A primary sear 46 is slidingly mounted in a well 48, which extends forwardly into block 40 from the rear end thereof, as best shown in FIG. 10, and a spring 50 biases the prirnary sear rearwardly respective to the block. The longitudinal displacement of primary sear 46 is limited, and rotational displacement prevented, through the cooperation of a longitudinal slot 52 in the primary sear with a pin 54 transversely disposed through block 40. Primary sear 46 is terminated at the rear end by a carn surface 56 which inclines downwardly and rearwardly and such rear end, noted at 57, is received by a notch 58 in a tail section 60 of hammer 32, when the hammer is in the retracted position and block 40 is pressed rearwardly by trigger 30, to hold the hammer retracted. A cam surface 62 on tail section 60 contacts cam surface 56 on primary sear 46 during retraction of hammer 32 to displace the primary sear forwardly out of interference therewith. Primary sear 46 snaps back to engage rear end 57 with notch 58 when the ha rnrner is fully retracted.

When trigger 30 is released and block 40 with primary sear 46 is displaced forwardly, rear end 57 is pulled out of notch 58, releasing hammer 32 which is almost immediately researed by a secondary sear 64 during initial displacement of the hammer to the striking position. Secondary sear 64 is pivotally mounted at the rear end on a transverse pin 66. The front end of secondary sear 64 has contact with a cam surface 68 on block 40 so as to be displaced downwardly to a release position when the block is pressed inwardly by trigger 30. Secondary sear 64 is pivoted upwardly to a holding position by a spring 70. Hammer 32 is held seared by secondary sear 64 through the contact of a forwardly facing lip 72 on the top side of the secondary sear with a rearwardly facing lip 74 forrned on the hub of the hammer.

When selector 36 is indexed for automatic fire, primary sear 46 is held inoperative, out of interference with hammer 32, as hereinafter described, and the hammer is conrolled by an automatic sear 76. Automatic sear 76 is of lever configuration and is located in the portion of channel 28 which is formed in flange 26. Automatic sear 76 is pivotally mounted on an upright stud 78 and a follower 80 extends u;wardly from the front end of the automatic sear, forwardly of such stud, for sliding contact with a cam slide 82 formed on the right side of a channel 81 in the bottom of slide member 13. Cam slide 82 is formed to pivotally dsplace automatic sear 76 from a holding to a release position when slide member 18 is adjacent bat tery position. Hammer 32 is controlled by automatic sear 76 through the cooperation of a rear tip 83 thereon with a ledge 84 formed in the hub of the hammer. When automatic sear 76 is in the holding position, rear tip 33 is positioned for contact by ledge 34 to hold hammer 32 re tracted and, when the automatic sear is in the release position, the rear tip is in registry with an annular clearance 86 formed in the right side of the hub of the hammer to free the hamrner for displacernent to the striking position. Annular clearance 86 forms a shoulder 87 on the left side thereof. When hammer 32 is released, rear tip 83 contacts shoulder 87 to hold automatic sear 76 in the release position until the hammer returns to the retracted position whereupon, under the influence of a spring-biased plunger 85, the automatc sear snaps back into the holding position under ledge 84.

Ledge 84 is located so as to be in contact with rear tip 33 and, when hammer 32 is pivoted slightly toward the striking position from the position it is held by secondary sear 64. Thus, automatic sear 76 acts as a safety, when selector 36 is indexed for semiautomatic fire, because hammer 32, if inadvertently released by trigger 30 before bolt assembly is in battery, Will be held retracted by the automatic sear until the bolt assembly reaches battery position, whereupon the automatic sear will be automatically actuated, as hereinbefore described, to release the hammer.

When firearm 12 is selected for automatic fire, it fires from an open bolt position with bolt assembly 15 being releasably held in recoil position by a bolt sear 88 which is mounted for vertcal displacement in the rear end of trigger housing 22. A trigger bar 90 pivotally mounted on pin 33 is cooperatively disposed between bolt sear 88 and trigger 30 for translating rearward displacement of the trigger to downward displacernent of the bolt sear to a release position and such trigger bar is positioned along the left-hand wall of channel 28. Bolt sear 88 is biased upwardly to a holding position by a spring 92. When bolt sear 88 is in the holding position, it is contactable by an end wall 94 of channel 81 to releasably hold bolt assembly 15 in recoil position.

Selector 36, as best shown in FIG. 9, includes a shaft 96 which is transversely mounted through trigger housing 22 so as to pass adjacent the rear ends of primary sear 46 and secondary sear 64 for cooperation therewith as hereinafter described. A lever 98 is mounted on the right end of shaft 96 outside of trigger housing 22 to provide means for manually turning the shaft. A detent 100 on the inside of lever 96 cooperates with three mating depressions, one of which is shown at 102, in the side of trgger housing 22 for indexing selector 36 in the automatic, semiautomatic or safe positions.

Mounted on shaft 96 adjacent the left end thereof is a semicrcular cam plate 103 which has camming cooperation with a stud 104 on trigger bar 90 for actuating the trigger bar so that bolt sear 88 is depressed in the release position when selector 36 is indexed in serniautomatic position. Thus, when firearm 12 is fired semiautomatically, it is fired from the closed bolt position.

In order for firearm 12 to fire automatically, primary sear 46 must be held inoperative so that hammer 32 will not be caught by the primary sear while trigger 30 is held pulled. Ths is accomplished by symmetrically slabbing shaft 96 on opposite sides to form a dametrical tongue porton 106 where adjacent primary sear 46 so that, when selector 36 is indexed in semiautomatic position, the tongue porton is horizontally disposed, as shown in FIG. 5, permtting the primary sear to pass freely under the tongue porton. When selector 36 is rotated 90 to automatc position, tongue porton 106 is vertically disposed, as shown in FIG. 6, and in cooperation with a notch 108 in the rear end of primary sear 46 to block displacement thereof to its holding position while trigger 30 is held pulled.

Firearm 12 is made safe against discharge by accidental displacement of trigger 30 through the cooperation of shaft 96 with a tang 110 which extends downwardly and rearwardly from the rear end of secondary sear 64 to contact the shaft. The contact of tang 110 with shaft 96 blocks pivotal displacement of secondary sear 64 by cam surface 68 of block 40, whereby rearward displacement of the block by trigger 30 is prevented by the blocking disposition of secondary sear 64 between such cam surface and shaft. A pair of chordal recesses 112 and 114 in shaft 96 permit pivotal displacement of secondary sear 64 When selector 36 is indexed for semiautomatic and automatic fire, respectively, and thereby trigger 30 is free to be pulled.

Operation When the firearm 12 is to be fired semiautornatcally, selector 36 is indexed in the semiautomatic position, whereby bolt sear 88 is held depressed through the cooperation of cam plate 103 with stud 104 on trigger bar 90. In semiautomatic fire, firearrn 12 fires from closed 4 bolt position and, therefore, when the firearm is ready for firing, bolt assembly 15 is in battery position, hammer 32 is releasably held retracted by secondary sear 64 and automatic sear 76 is pivoted by cam slide 82 to the release position thereof with rear tip 83 in registry with elearance 86.

Firearm 12 is fired by pulling trgger 30 which presses block 40 inwardly causing cam surface 68 thereon to pivot secondary sear 64 and thereby displace lip 72 thereon frorn lip 74 on hammer 32. The released hammer 32 swings upwardly under the bias of spring 34 to strike firing pin 20 for discharge of the chambered cartridge. The displacement of hammer 32 to striking position is uninterrupted by automatic sear 76 which was held in its release position through the cooperation of cam slide 82 with follower 80 as shown in FIG. 2. The resulting discharge causes bolt assembly 15 to recoil with slide member 18 cammingly contacting hammer 32 to swing the hammer downwardly to the retracted position. As hammer 32 swings trom striking position, shoulder 87 is moved into position for contact by rear tip 33, whereby automatic sear 76 is held in the release position until the hammer is retracted. When hammer 32 reaches retracted position, rear tip 83 snaps under ledge 84, as shown in FIG. 8, and rear end 57 of primary sear 46 snaps into notch 58 as shown in FIG. 4. Release of trigger 30 permits forward displacement of block 40 which carries primary sear 46 forwarclly also to Withdraw rear end 57 from notch 58. Consequently, hammer 32 is released trom primary sear 46 for displacernent to striking position but is mrnediately researed by secondary sear 64 and ready to fire another round When trigger 30 is pulled.

When firearm 12 is selected for automatic fire, selector 36 is indexed in automatic position and bolt assembly 15 is seared in the recoil position by bolt sear 88 as shown in FIG. 7. Hammer 32 is releasably held retracted by automatic sear 76 and primary sear 46 is made inoperative by selector 36 as shown in FIG. 6. Firearm 12 is fired by pulling trigger 30 which pivots trigger bar against bolt sear 88 for displacement thereof to the release position. When the released bolt assembly 15 reaches battery position, cam slide 82 acts against follower 80 to pivot automatic sear 76 into registry with clearance 86, as shown in FIG. 2, for release of hammer 32 into striking contact with firing pin 20. During the ensuing recoil travel of bolt assembly 15 and pivotal displacement of hammer 32 to the retracted position, automatic sear 76 is held in release position by the contact of shoulder 87 with rear tip 83. When hammer 32 reaches retracted position, rear tip 83 snaps under ledge 84 to hold the hammer retracted until bolt assembly 15 returns to battery position, whereupon cam slide 82 acts against follower 80 to actuate automatic sear 76 for firing another round. Firing is continued until trigger 30 is released, whereupon bolt sear 83 is released for upward displacement to its holding position to stop bolt assembly 15 in recoil position during the next cyclic travel thereto.

Although a particular embodiment of the inventon has been described in detail herein, it is evident that many variations may be devised Within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

1. In a firearm, a bolt assembly mounted for reciprocation between a battery and a recoil position, a firing pin actuatably disposed in said bolt assembly, and a firing mechanism including a hammer mounted for pivotal displacement beween a retracted and a firing pin striking position, a trigger actuatable from a normal to a pulled position, semiautomatic sear means operationally disposed between said trigger and said hammer for selective cooperation therewith to provide for semiautornatic fire, automatic sear means operationally disposed between said bolt assembly and said hammer to provide for automatic fire, said automatic sear means including an automatic sear, a rear tip of said automatic sear, means for mounting said automatic sear for pivotal disp-lacen1ent between a holding and a release position, a spring biasing said automatic sear to the holding position, a follower mounted on said automatic sear, a carn slide formed 011 said bolt assembly to cooperate with said follower for actuating said automatic sear to the release position when said bolt assembly is adjacent battery position, a ledge formed on said hamrner and arranged for contact with said rear tip when said automatic sear is in the holding position thereof for retaining said hammer in the retracted position, an annular clearance formed on said hammer to register with said rear tip when said automatic sear is in the release position to free said harnrner for displace- 1nent to the striking position and a shoulder formed on said clearance and disposed for sliding contact with said rear tip for holding said automatic sear in the release position thereof during displacernent of said ham1ner from the striking to the retracted position.

2. The firearrn as defined in claim 1 and including a selector operationally disposed in cooperation With said sernautomatic sear rneans and said automatic sear means to selectively provicle for automatic and semiautomatic fire and to safety the irearm against accidental discharge by said trigger.

3. The firearm as defined in claim 2 and including a bolt sear mounted for translational displacement to releasably engage said bolt assembly in the recoil position, a trigger bar operatonally disposed between said bolt sear and said trigger to translate pivotal displacement of said trigger to the pulled position to displacement of said bolt sear to a bolt release position, and cooperating means on said trigger bar and said selector for actuating said bolt sear to the bolt release position When said selector is indexed for semiautomatic fire.

4. The firearm as defined in claim 3 wherein said semiautomatic sear means include a primary sear mounted for translational displacement between a holding and a release position respective to said harnrner, a rear end of said primary sear, a notch disposed in said l1ammer for receiving said rear end when said prirnary sear is in the holding position to hold said hammer retracted, a block operationally disposed between said trigger and said primary sear for dsplacing said primary sear to the holding position when said trigger is actuated to the pulled position, a secondary sear mounted for pivotal displacement between a holding and a release position respectve to said harnrner, carnming means on said block contacting said secondary sear for displacing said secondary sear to the release position When said trigger is actuated to the pulled position, a first lip on said secondary sear disposed for contact With a second lip on said hammer when said secondary sear is in the holding position to releasably hold said hammer retracted after release by said primary sear, and wherein said ledge is located so as to be contacted by said rear tip after said harnrner is released by said secondary sear.

5. The fireann as defined in claim 4 Wherein said selector is provided With tongue means disposed in cooperation With a notch in said primary sear to prevent dsplacement thereof to the holding position by actuation of said trigger to the pulled position When said selector is indexed for automatic fire, andcooperating means on said selector and on said secondary sear for preventing pivotal displacernent thereof to the release position and block displacernent of said trigger to the pulled postion when said selector is indexed to safety the firearm against acci dental discharge by said trigger.

References Cited by the Examiner UNITED STATES PATENTS 2464,418 3/49 Sefried 89-140 2,471779 5/49 Roemer 89142 2,482,758 9/49 Gaidos 89140 BENJAMIN A. BORCHELT, Prmary Examiner. FRED C. MATTERN, JR., Examner. 

1. IN A FIREARM, A BOLT ASSEMBLY MOUNTED FOR RECIPROCATION BETWEEN A BATTERY AND A RECOIL POSITION, A FIRING PIN ACTUATABLY DISPOSED IN SAID BOLT ASSEMBLY, AND A FIRING MECHANISM INCLUDING A HAMMER MOUNTED FOR PIVOTAL DISPLACEMENT BETWEEN A RETRACTED AND A FIRING PIN STRIKING POSITION, A TRIGGER ACTUATABLE FROM A NORMAL TO A PULLED POSITION, A SEMIAUTOMATIC SEAR MEANS OPERATIONALLY DISPOSED BETWEEN SAID TRIGGER AND SAID HAMMER FOR SELECTIVE COOPERATION THEREWITH TO PROVIDE FOR SEMIAUTOMATIC FIRE, AUTOMATIC SEAR MEANS OPERATIONALLY DISPOSED BETWEEN SAID BOLT ASSEMBLY AND SAID HAMMER TO PROVIDE FOR AUTOMATIC FIRE, SAID AUTOMATIC SEAR MEANS INCLUDING AN AUTOMATIC SEAR, A REAR TIP OF SAID AUTOMATIC SEAR, MEANS FOR MOUNTING SAID AUTOMATIC SEAR FOR PIVOTAL DISPLACEMENT BETWEEN A HOLDING AND A RELEASE POSITION, A SPRING BIASING SAID AUTOMATIC SEAR TO THE HOLDING POSITION, A FOLLOWER MOUNTED ON SAID AUTOMATIC SEAR, A CAM SLIDE FORMED ON SAID BOLT ASSEMBLY TO COOPERATE WITH SAID FOLLOWER FOR ACTUATING SAID AUTOMATIC SEAR TO THE RELEASE POSITION WHEN SAID BOLT ASSEMBLY IS ADJACENT BATTERY POSITION, A LEDGE FORMED ON SAID HAMMER AND ARRANGED FOR CONTACT WITH SAID REAR TIP WHEN SAID AUTOMATIC SEAR IS IN THE HOLDING POSITION THEREOF FOR RETAINING SAID HAMMER IN THE RETRACTED POSITION, AN ANNULAR CLEARANCE FORMED ON SAID HAMMER TO REGISTE WITH SAID REAR TIP WHEN SAID AUTOMATIC SEAR IS IN THE RELEASE POSITION TO FREE SAID HAMMER FOR DISPLACEMENT TO THE STRIKING POSITION AND A SHOULDER FORMED ON SAID CLEARANCE AND DISPOSED FOR SLIDING CONTACT WITH SAID REAR TIP FOR HOLDING SAID AUTOMATIC SEAR IN THE RELEASE POSITION THEREOF DURING DISPLACEMENT OF SAID HAMMER FROM THE STRIKING TO THE RETRACTED POSITION. 